This invention relates to a random copolymer prepared from cyclic monomers of glycolide and trimethylenecarbonate. The random copolymer may also include other cyclic monomers such as lactide, caprolactone, and p-dioxanone.
This invention also relates to compositions useful as a coating and lubricating finish for surgical devices, preferably for multifilament bioabsorbable sutures.
A block copolymer of glycolide and trimethylenecarbonate is known in the preparation of a synthetic absorbable suture, e.g. as disclosed in U.S. Pat. Nos. 4,243,775 and 4,300,565. These patents are incorporated herein by reference. The block copolymer disclosed in the prior art is highly crystalline, high melting (more than about 200.degree. C.), and is a fiber forming material. The block copolymer exhibits good physical properties and good absorption times when implanted in living animals.
It is known that suture materials are often coated with various substances to improve their handling characteristics, for example U.S. Pat. No. 4,027,676 and 4,185,637 teach the use of a composition comprising a bioabsorbable polymer and a fatty acid salt for suture coating application, and U.S. Pat. No. 4,047,533 describes the use of water soluble poly(alkylene oxide)s as a coating for multifilament bioabsorbable sutures. However, there is a constant research effort in this field to improve suture handling characteristics. For example, a survey included in U.S. Pat. No. 4,047,533 outlines several other approaches which are useful in improving the knot tying performance of sutures. All of the above patents are incorporated herein by reference.
It is an object of this invention to provide a random copolymer of glycolide and trimethylene carbonate containing up to about seventy-five weight percent of glycolide. The random copolymer can be processed by a solution method or by melting it at a moderate temperature to form a film and various articles.
Another object of this invention is to provide bioabsorbable, water insoluble coatings for multifilament sutures or implantable devices. The preferred coating systems may be applied to any suture material where it is desired to improve fiber lubricity and suture knot rundown characteristics. The coating is particularly useful with synthetic absorbable multifilament sutures composed of polylactide, polyglycolide, copolymers of lactide and glycolide, copolymers of glycolide and trimethylene carbonate, poly(p-dioxanone), poly(alkylene oxalate), and copolymers of glycolide and alkylene oxides, etc.